The present invention relates to a hinge, particularly for seats with adjustable backs.
Hinges of this general type are known in the art. A known hinge includes two hinge parts which are connected with one another by a shaft member defining their pivot axis, wherein the position of both hinge parts is determined by a transmission forming a device for adjusting an fixing the hinge parts relative to one another. In the known hinge, this device includes an eccentric having an inclined surface and arranged on the shaft member for joint rotation therewith, and a bearing associated with a gear supported on the eccentric and having an adjusting surface on which the surface of the eccentric abuts. The shaft member together with the eccentric is axially displaceable with the aid of an accumulator for obtaining a radial displacement between two hinge parts. Such a hinge is disclosed, for example in the German Auslegeschrift No. 2,326,223. One of the hinge parts in this hinge is connected with a seat member, whereas the other of the hinge parts is connected with the back member. The hinge part connected with the seat member is connected for joint rotation with a spur gear engaging with an inner gear which, in turn is connected for joint rotation with the hinge part of the back member. The hinge part of the back member is supported on a central portion of the shaft member. The latter has an eccentric portion which supports the spur gear with interposition of a bush. The eccentric portion of the shaft member has in the region of its greater eccentricity a wedge-shaped adjusting surface which is adjacent to the guide surface extending normal thereto. The eccentric portion is surrounded by a ring which has in its interior lateral guiding surfaces extending to the eccentric portion and an inner wedge-shaped adjusting surface. An accumulator is fixed in axial direction on the central portion of the shaft member and loads the eccentric portion so that the toothing of the spur gear and the inner toothed rim are pressed into one another. Thereby the play of toothing, on the one hand, and the bearing play between the shaft member and the hinge parts, on the other hand, is eliminated. In this position the turning of the hinge parts is very difficult inasmuch as the friction force is considerably increased because of the biasing. For this reason an eccentric disk device is arranged between the central portion of the shaft member and the adjusting handle arranged thereon. With this device for beginning the adjusting movement on the turning handle, the shaft member is displaced against the action of the accumulator in axial direction in the releasing sense. Thereby, the active eccentricity of the eccentric bush surrounding the eccentric portion is reduced to such an extent that an easy adjustment of the spur gear in the tooth play guaranteed in the inner gear is performed. After the adjustment step, the adjusting handle is insignificantly rotated back in order to return the cam disk device into its initial position, so that the accumulator returns the shaft member with the eccentric portion into a tensioned position eliminating radial play. In the known hinge it is possible to eliminate the radial play in the case of fixation. However, the required axial displacement of the shaft member is performed by the additional means formed as the cam disk device. Moreover, the tensioned position is not attained automatically by pure releasing of the adjusting handle. Instead, the operator, after termination of the adjustment movement proper, must rotate back the adjustment handle by movement corresponding to the initial adjustment movement in order to compensate for the radial play in the fixation case.